Amazon Polishes Up Its iPad Kindle App. While its Fire tablet is selling well, Amazon is clearly taking no chances with its app on the most popular tablet—the iPad: The firm has just added a slew of new features and fixes to the iPad Kindle app, from a new design for magazines to print replica textbooks to "seamless integration of personal documents," which is an expansion of its mail-yourself-your-docs service. Meanwhile, Apple is rumored to be launching its iPad 3 soon. —KE

TripAdvisor Goes Public. TripAdvisor began trading on NASDAQ today under the symbol TRIP. The high-profile site was formerly part of Barry Diller's InterActive Corp. empire. TripAdvisor had $486 million in 2010 revenue and the valuation of the IPO is approximately $4 billion. In an extra bit of good news for the firm's employees, Standard and Poor's announced that TripAdvisor is being named to the S&P 500. —NU

—Updated 10:15 a.m. EST

"The Hobbit" Trailer Now Out. Weta Digital, #40 on the Fast 50 2009, Fast Company's list of the world's Most Innovative Companies, is bringing more Middle Earth adventures to life in the film adaptation of J. R. R. Tolkein's The Hobbit. The digital effects company was behind the stunning battle scenes in the Lord of the Rings trilogy directed by Peter Jackson. The trailer for Jackson's The Hobbit is out now, and the movie will come to U.S. theaters in December 2012. —NS

Lovefilm Signs Streaming Deal With Sony. Preparing for Netflix's entry into Lovefilm's home market, the U.K. video service has signed a deal with Sony Pictures Television for exclusive rights to stream hit movies like The Social Network, Salt, and 2012. It's the latest of a series of streaming deals its made with companies that include the BBC, Lionsgate, MGM, and Miramax. —NS

Layar Unveils AR App For All Photos. Augmented reality tech company Layar has added a new app to its collection of data-layering tools for video and images. With the Stiktu app, you can snap pictures of anything, and add a layer of text, or a sticker, or a sketch to it. The image can then be sent off to friends via Twitter or Facebook, who can can view it, tag it, or favorite it, TheNextWeb explains. The app is available for Android and iOS in nine countries in Europe. —NS

Chinese Hackers Break Into U.S. Chamber Of Commerce. Hackers in China infiltrated the U.S. Chamber Of Commerce and gained access to information about its 3 million members last year. Though it's not yet clear how much data the hackers viewed, initial reconnaissance indicates that they homed in on four Asia policy experts and stole their emails, the Wall Street Journal reports. —NS